Various systems exist for delivering digital content to receivers and other content playback devices. These include, for example, in the audio domain, satellite digital audio radio services (SDARS), digital audio broadcast (DAB) systems, high definition (HD) radio systems, and streaming content delivery systems, to name a few, or in the video domain, for example, video on-demand, cable television, and the like.
Since available bandwidth in a digital broadcast system and other content delivery systems is often limited, efficient use of transmission bandwidth is desirable. For example, governments allocate to satellite radio broadcasters, such as Sirius XM Radio Inc. in the United States, a fixed available bandwidth. The more optimally it is used, the more channels and broadcast services that can be provided to customers and users. In other contexts, bandwidth accessible to a user is often charged on an as-used basis, such as, for example, in the case of many data plans offered by cellular telephone services. Thus, if customers use more data to access a music streaming service on their telephones, for example, they pay more. An ongoing need therefore exists for digital content delivery systems of every type to transmit content in an optimal manner so as to optimize transmission bandwidth whenever possible.
One illustrative content delivery system is disclosed in U.S. Pat. No. 7,180,917, under common assignment herewith. In that system, content segments such as full copies of popular songs are pre-stored at various receivers in a digital broadcast system to improve broadcast efficiency. The broadcast signal therefore only need include a string of identifiers of the songs stored at the receivers as part of a programming channel, as opposed to transmitting compressed versions of full copies of those songs, thereby saving transmission bandwidth. The receivers, in turn, upon receipt of the string of song identifiers, selectively retrieve from local memory and then playback those stored content segments corresponding to the identifiers recovered from the received broadcast signal. The content delivery system disclosed in U.S. Pat. No. 7,180,917, however, does have disadvantages. For example, while broadcast efficiency is improved, storing full copies of songs on the receivers is a clumsy solution. It requires using large amounts of receiver memory, and continually updating the song library on each receiver with full copies of each and every new song that comes out. To do this requires using the broadcast stream or other delivery method, such as an IP connection to the receiver over a network or the Internet, to download the songs in the background or at off hours to each receiver, and thus requires them to be on for such updates.
Thus, a need exists for a method of improving the efficiency of broadcasting, streaming or otherwise transmitting content to receivers, so as to optimize available bandwidth, and significantly increase the available channels and/or quality of them, using the same, now optimized, bandwidth, without physically copying an ever evolving library of songs and other audio content onto each receiver, while at the same time minimizing the use of receiver memory and the need for updates.